conference schedule and program with abstracts - Horticulture ...

P-45
Preliminary observations on the role of sirtuin genes in grapevine physiology
M. Cucurachi 1 , B. Hubbard 2 , L.G. Kovacs 3 , M. Busconi 1 , C. Fogher 1 , R. Oláh 4 , P.
Winterhagen 5 , A. Perl 6 , D.A. Sinclair 2 , L. Bavaresco* 7
1 Istituto di Agronomia, Genetica e Coltivazioni Erbacee, Sezione Botanica e Genetica Vegetale,
Università Cattolica del Sacro Cuore, Piacenza, Italy; 2 Harvard Medical School, Pathology,
Boston, USA; 3 Department of Fruit Science, Missouri State University, Mountain Grove,
Missouri, USA; 4 Department of Genetics and Plant Breeding, Corvinus University of Budapest,
Hungary; 5 Institute of Specialty Crops and Crop Physiology Fruit Sciences, University of
Hohenheim, Stuttgart, Germany; 6 Institute of Plant Sciences, The Volcani Center, Bet Dagan,
Israel; 7 Istituto di Frutti-Viticoltura, Università Cattolica del Sacro Cuore, Piacenza, Italy
*Corresponding author: luigi.bavaresco@unicatt.it
The sirtuin/Sir2 (Silent information regulator 2) family of NAD+-dependent deacetylases and
mono-ADP-ribosyltransferases play a part in various aspect of cellular metabolism in eukaryotes.
Their role in mediating the calorie restriction effect extending longevity and extending lifespan
in Saccharomyces cerevisiae, Caenorhabditis elegans, and Drosophila melanogaster is well
known. Information about their occurrence and role in plant genomes, however, is scarce.
Recently, two putative sirtuin genes encoding a SIRT4-like protein on chromosome 7 and a
SIRT7-like protein on chromosome 19, were identified in the V. vinifera genome. These two
genes appear to be present in single copy as shown by Southern blotting analysis.
RT-PCR results demonstrated a baseline transcription level of both genes in different plant
organs. Sirtuin discovery in the grape genome is intriguing because stressed grapevine cells
synthesize compounds with hydroxylated trans-stilbene ring structure, such as, resveratrol (trans
3,3′,5-trihydroxystilbene) which is able to activate sirtuins in yeast, in C. elegans and D.
melanogaster. The aim of our research is the identification of the function and activity of both
putative sirtuin proteins in grapevine. We will accomplish this by investigating their interaction
with resveratrol using in vitro and in vivo approaches and assaying changes in their expression
levels in response to various abiotic stress conditions. In vitro assays demonstrated a very weak
NAD+-dependent deacetylase activity of both sirtuins and no activation by resveratrol.
Moreover, neither protein displayed ADP-ribosyltransferase activity. The in vivo function will be
investigated by transforming whole grapevine plants and cell cultures and by the omplementation
of a S. cerevisiae sir2Δ mutant.
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